Windows Server 2025 tightens several IIS defaults that affect request filtering, TLS, and logging. Administrators running production .NET workloads should apply the new baseline immediately after installation rather than inheriting legacy configurations.

The fastest and most repeatable way to enforce the baseline remains PowerShell. The WebAdministration and IISAdministration modules together expose every setting that previously required manual UI clicks or appcmd.exe.

#Apply the 2025 Request-Filtering Baseline

Start by enabling the strict request-filtering rules introduced in the 2025 release. These rules block common reconnaissance patterns before they reach application code.

powershell 
Import-Module WebAdministration
Set-WebConfigurationProperty -Filter /system.webServer/security/requestFiltering -Name allowHighBitCharacters -Value $false
Set-WebConfigurationProperty -Filter /system.webServer/security/requestFiltering -Name allowDoubleEscaping -Value $false

#Enforce Modern TLS Settings

Windows Server 2025 disables TLS 1.0 and 1.1 by default at the OS level. Confirm IIS inherits these settings and add HSTS for sites that require it.

  • Verify Schannel registry keys match Microsoft 2025 guidance
  • Enable HTTP Strict Transport Security via the HSTS module
  • Remove weak cipher suites from the IIS binding

#Integrate with Active Directory Application Pools

When application pools run under domain accounts, use the new PowerShell cmdlets to set the correct identity and SPN registration automatically.

powershell 
Set-IISAppPool -Name "DefaultAppPool" -ProcessModelIdentityType SpecificUser -ProcessModelUserName "DOMAIN\iisapppool" -ProcessModelPassword (Read-Host -AsSecureString)

#Verification and Logging

After applying changes, run a short audit script to confirm settings and export the current configuration for change tracking.

Apply these steps on every new Windows Server 2025 instance before moving workloads. Store the scripts in source control so future servers receive identical hardening without manual review.